very easy, when you first buy bitcoin means then you have invested with bitcoin, and just have to hold it.
if you want to make bitcoin, as a future investment, you just have to hold it for as long as possible.
Investing doesn't always mean that you have to hold your bitcoin for the rest of your life. If the time is right for you already, then you can always sell it at good price. Besides, you can always buy bitcoins at a lower price since it will never cease to encounter crisis.